Jessie was born May 31, 1824, in Cherry Grove, Virginia, the daughter of Thomas Hart and Elizabeth McDowell Benton. By the time she was five years old, Jessie was living in the nation's capital. She absorbed her early education from her father, a senator from Missouri who was renowned as the Great Expansionist.

Jessie stuck to him "like a pet doggie," and Senator Benton shared with her the wonderland of books and maps in the valise that always accompanied him on their trips to and from Missouri and Virginia. She began, too, to share his dream of a nation stretching from ocean to ocean.

After attaining some fluency in French and Spanish, Jessie helped in the translation of government documents. In 1838, the Bentons decided that the rambunctious Jessie needed the discipline of a fashionable girls' school, and she was enrolled at Miss English's Female Seminary near Washington, D.C. She despised the school, mostly because of the class discrimination she observed there.

Senator Benton became acquainted with John Charles Fremont, a young topographical engineer who shared similar expansionist dreams, and introduced him into the Benton home. Fremont escorted Jessie's older sister, Liz, to a school concert where he saw Jessie and fell in love at first sight.

Jessie's parents forbade them to see one another, but her love for John was not only a passionate impulse but a political statement. They were married in secret on October 19, 1841, in Washington, D.C. Senator Benton was persuaded by his ailing wife to accept the marriage, and the couple moved into the Benton house.

Fremont left pregnant Jessie in the spring of 1842, leading his first expedition to mark the trails to the West. He returned days before the birth of Elizabeth Benton (known as Lily) on November 15, 1842. Jessie, intensely interested in the details of his expedition, became his recorder, making notes as Fremont described his experiences and then writing them out. She added human-interest touches that made the printed reports bestsellers. So she "slid into her most happy life work," interpreting her husband and his actions for a public eager for information about the opening of the West.

At the time of the court martial trial during which Fremont attempted to defend his actions in the Bear Flag Revolt in California, Jessie gave birth to a second child, Benton, on July 24, 1848, whose death as an infant she blamed on General Kearney, Fremont's accuser.

In the spring of 1849, traveling over the Isthmus of Panama with her 6-year-old daughter, Jessie went to California to meet her husband. John Charles was born April 19, 1851, at Las Mariposas in California. Anne Beverly, born in Paris, France, on February 1, 1853, died on July 11 of that same year.

On May 17, 1855, her fifth and last child, Francis Preston, was born. At the same time her husband agreed to be the first presidential nominee for the new Republican Party. His campaign song included the platform "Free Speech, Free Press, Free Soil and Fremont," but its chorus was "We'll give 'em Jessie."

After his defeat by Buchanan, they moved to Black Point, overlooking the Golden Gate in San Francisco, where they lived until the Civil War at which time Fremont was named Major General in command at St. Louis.

Following the War, they retreated to Pocoho on the Hudson River near Terrytown, New York. In the financial panic of 1873, Fremont, who had invested heavily in railroad stock, lost everything and the family moved to New York City, where they were supported by the money Jessie earned from her published articles and stories in popular magazines.

In 1878, President Hayes appointed Fremont as the 5th Territorial Governor of Arizona.

Jessie, with her daughter Lily, her son Frank, her Irish maid Mary, her cook Ah Chung, and a dog named Thor, arrived in Prescott on October 6, 1878. Jessie stayed only one year, using the effect of the high altitude on her health as an excuse, and moved back to New York City where she was in constant correspondence not only with her daughter and husband, but with officials in Washington, D.C. She was joined in New York by her husband and daughter in 1881, when Fremont resigned as territorial governor.

They decided to move back to California, and Jessie and Lily were in Los Angeles when she learned of her husband's death on July 28, 1890, in New York City.

The next July the two ladies moved into a house built for them in Los Angeles by a committee of California women. There Jessie died on December 27, 1902. She was buried with her husband on the banks of the Hudson River in New York.